Recently, correlated double sampling (CDS) for removing noise from a signal outputted from a charge coupled device (CCD), dark current correction, automatic gain control (AGC), and analog front end (AFE) including analog digital converter (ADC) for conversion into a digital image signal Vi have become widespread. The ADC of the AFE conventionally has 10-bit gradation, but 12-bit or 14-bit gradation has become generalized.
Further, improvements have been made to a complementary metal oxide semiconductor (CMOS) image pickup device including a drive circuit together with a readout circuit to achieve a high-speed readout.
In addition, as the integration of digital signal processing circuits progresses, it becomes possible to easily perform an operation of storing and arithmetically processing output signals of a plurality of lines not only by a memory integrated digital signal processor (DSP) for processing only images, but also by an inexpensive general-purpose field programmable gate array (FPGA). A megapixel camera with more than 1 million pixels, a high definition television (HDTV) camera, a high-speed image pickup HDTV camera, a HDTV camera with a recording unit, a HDTV camera with an Internet Protocol (IP) transmission unit, and a higher resolution 2K×4K camera or 4K×8K camera including an uncompressed recording device using ultra high definition television (UHDTV) or hard disk drive (HDD) have also become commercialized. Also in a flat image display device, UHDTV display of 2K×4K or 4K×8K of higher definition, high-speed display and an ultra-thin profile have been achieved.
Further, a conventional image signal processing apparatus determines a diagonal direction of a contour of an image signal. Based on the determination result of the diagonal direction of the contour, the apparatus generates interpolation pixel data by using a plurality of original pixel data in the image signal, and generates an image signal with an increased number of pixels. The characteristics for generating high frequency signal components vary depending on the determination result of the diagonal direction of the contour (see Patent Document 1).
Further, conventionally, there is an image processing apparatus configured to suppress a moiré of diagonal aperture correction (see Patent Document 2).
In addition, there are image pickup devices for multi-scan line vertical contour correction and multi-pixel horizontal contour correction (see Patent Document 3).
Patent Document 1: Japanese Patent Application Publication No. 2013-207673
Patent Document 2: Japanese Patent Application Publication No. 2007-336384
Patent Document 3: Japanese Patent Application Publication No. 2013-008260